When one or more combustion-type heating appliances are housed within an interior building area, that interior area must be provided with a combustion air inlet in order to supply the area with sufficient exterior air to support the desired combustion. However, the admission of exterior air to such an interior building area admits cold air during cold weather and hot air during the summer, even during periods of non-usage of the combustion-type heating appliances for which the inlet is designed to provide a supply of combustion air. Accordingly, in the interest of saving energy, several different forms of damper actuating mechanisms heretofore have been provided for automatically closing such a combustion air inlet during periods of non-usage of the associated combustion-type heating appliances.
However, many of these actuating mechanisms rely upon fixed pivot swinging of the associated dampers and solenoid actuators whose stroke may not be perfectly matched to the desired opening and closing of the associated damper with the result that the damper may not fully open or may not fully close in a reliable manner. Examples of previously known forms of damper actuating mechanisms and other similar devices including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat Nos. 2,224,705, 2,357,642, 3,773,028, 4,055,699, 4,108,369 and 4,143,811.